The present invention relates to improvements in technique of a developing unit replacing means, toner supply means, cleaning means and used toner recovery means which are installed in an image forming apparatus, especially a color image forming apparatus having a plurality of developing units on the circumferential surface of an image forming body.
In a color image forming apparatus, image processing is carried out with respect to a plurality of colors. Accordingly, the color image processing apparatus is provided with a plurality of developing units, each unit having the function of developing a mono-color, and also provided with a plurality of toner accommodating containers for supplying toner to the developing units.
The frequency of maintenance of a group of developing units is high. Accordingly, they are integrated into one process cartridge together with a cleaning unit so that they can be easily taken out from the image forming apparatus for maintenance. Therefore, the developing units are connected with or disconnected from the toner accommodating containers and the used toner recovery box each time the cartridge is detached from the image forming apparatus.
However, the construction of a connecting section between the developing units and toner accommodating units or used toner recovery box is complicated, because the leakage of toner must be prevented. Therefore, the handling operation requires much time and labor. Further, it is impossible to avoid the leakage of a small amount of toner during the handling operation of the connecting section. The leaked toner is accumulated over a long period of time, and the inside of the image forming apparatus is stained with the accumulated toner, which deteriorates image quality.
In order to overcome the above disadvantages, the following method is adopted:
The toner accommodating containers and developing units are integrated into one body, and the integrated body is assembled to a process cartridge.
However, as described before, it is necessary to install 3 or 4 developing units in the color image forming apparatus, so that the size and weight of the process cartridge are increased, and further it is necessary to take out the process cartridge from the apparatus each time toner is supplied. For these reasons, the aforementioned method is disadvantageous in that the handling is difficult and it takes time and labor to maintain the process cartridge.
The present invention has been achieved to solve the above problems. The apparatus of the present invention does not require a complicated connection mechanism for toner supply, and further the process cartridge is made compact, so that it can be easily moved to the outside of the apparatus. Furthermore, toner can be easily supplied when the process cartridge is moved by a short distance. In the case where the used toner recovery box is taken out, it can be removed from the process cartridge together with the cleaning unit. When toner is supplied or only the used toner box is taken out so as to be processed, the direction of the process cartridge is restricted so that the toner can not be spilt. As a result, the inside and outside of the image forming apparatus are not stained with leaked toner. It is a first object of the present invention to provide the color image forming apparatus having advantages described above.
It is also the first object of the present invention to provide a color image forming apparatus in which the developing units are assembled to the process cartridge, and under the condition that the process cartridge is attached to the image forming apparatus, toner can be supplied from a side at which the image forming apparatus is operated by an operator.
In general, a plurality of developing units having color toners of various colors are installed in a color image forming apparatus. For the cleaning, inspection and replacement operations of the developing units, they are integrated into a process unit together with a photoreceptor, or alternatively they are individually installed in the color image forming apparatus in such a manner that they can be easily attached to or detached from the apparatus, and further a conveyance passage of transfer sheets can be opened when the developing units are detached.
However, as is well known, a side of the developing unit opposed to the photoreceptor is widely open. Therefore, when the developing unit is inclined or vibrated, the accommodated toner drops or scatters from the unit, so that the conveyance surface of a transfer sheet is stained with toner, which deteriorates image quality. In the case where color toner is supplied to the developing unit, the conveyance surface of a transfer sheet is stained with toner in the same manner.
The present invention has overcome the above disadvantages. It is a second object of the present invention to provide a color image forming apparatus in which the developing units can be attached to and detached from the apparatus without the dropping and scattering of color toner, so that the operations of jam clearance and toner supply can be safely carried out.